1. Field of the Invention
The present invention relates to an image forming apparatus that employs an electrophotographic system, an electrostatic recording system, or the like.
2. Description of the Related Art
Up to now, for example, as an image forming apparatus of an electrophotographic system, an image forming apparatus that adopts an intermediate transfer system in which, after a toner image formed on a photosensitive member is primarily transferred onto an intermediate transfer member, the toner image is secondarily transferred onto a transfer material such as paper has been proposed. In general, a primary transfer member is provided for a primary transfer part, and a secondary transfer member is provided for a secondary transfer part. Voltages from independent power sources are applied to the primary transfer member and the secondary transfer member, respectively and potentials for primary transfer and secondary transfer are respectively generated at the primary transfer part and the secondary transfer part.
Japanese Patent Laid-Open No. 2012-137733 proposes an image forming apparatus that adopts the intermediate transfer system and that causes a current to flow in a circumferential direction of the intermediate transfer member from the secondary transfer part and performs both primary transfer and secondary transfer. In this case, an endless belt having a conductivity at which a current can flow in the circumferential direction is used as the intermediate transfer member, and a voltage is applied to the secondary transfer member to cause the current to flow through the belt.
In addition, up to now, the image forming apparatus executes various adjustment processes for an image quality adjustment, a status check, and the like. For example, when images are continuously formed, the image forming processing may be temporarily interrupted to perform the adjustment processing in a case where a certain condition (processing execution condition) is met. In this case, after the adjustment processing is ended, the image forming apparatus resumes the interrupted image formation. As an example of the adjustment processing, processing of periodically supplying toner to a cleaning unit has been proposed to suppress turn-up or the like of a cleaning blade that removes toner from the photosensitive member. Since the toner is periodically supplied to the cleaning unit, lubrication between the cleaning blade and the photosensitive member is realized (hereinafter, this processing may also be referred to as “discharge processing”).
A timing for executing the discharge processing is generally determined on the basis of a number of sheets subjected to image formation, a printing ratio, or the like. The image forming apparatus temporarily interrupts the image forming processing when the processing execution condition (discharge processing execution condition) set by using the above-described number of sheets subjected to the image formation, the printing ratio, or the like as an index is met, and forms on the photosensitive member a toner image to be supplied to the cleaning unit. This toner image is supplied to the cleaning unit without being transferred to the intermediate transfer member while a potential generated at the primary transfer part is set to have the opposite polarity with respect to the polarity upon the primary transfer. The image forming apparatus then resumes the image formation after the discharge processing is ended.
According to the configuration in which the power sources are respectively provided for the primary transfer part and the secondary transfer part, it is possible to generate potential having predetermined polarities at the primary transfer part and the secondary transfer part by independently controlling respective voltages and currents. With such configuration, in a case where the adjustment processing such as the discharge processing is executed, the potential having a predetermined polarity can be independently generated at the primary transfer part irrespective of the polarity of the potential generated at the secondary transfer part, and the adjustment processing can be executed.
However, as disclosed in Japanese Patent Laid-Open No. 2012-137733, since the respective polarities of the potentials generated at the primary transfer part and the secondary transfer part cannot be independently controlled, it is difficult to execute the adjustment processing.